1. Technical Field
The disclosure relates to an assembly of a pneumatic tire and a rim, and more specifically relates to an assembly of a pneumatic tire and a rim having a noise suppressing body decreasing tire noises inside a tire cavity.
2. Related Art
In the related art, in order to decrease tire noises, it has been proposed to provide a noise suppressing body such as a sound absorbing material inside a tire cavity.
For example, JP-A-2008-080846 discloses a configuration where the sound absorbing material formed of flexible polyurethane foam is adhered to an inner surface of a tire. In this disclosure, the sound absorbing material is configured to have a first sound absorbing layer of the inner surface side of the tire and a second sound absorbing layer laminated on an inner peripheral side thereof and having lower density than the first sound absorbing layer, whereby achieving weight lightening of the sound absorbing material. However, in the sound absorbing material adhered to the inner surface of the tire, a sound absorbing effect is not expected to be sufficient with respect to sound waves generated by an input from a road surface and transmitted from a tread part into a tire cavity, and thereby a poor effect is expected in decreasing the tire noises.
In contrast, JP-A-2011-006063 discloses that a plurality of overlapped sound absorbing material layers is disposed into the tire cavity. In addition, WO 2009/124182 discloses that the sound absorbing material layers are disposed into the tire cavity, and a space between the sound absorbing material layers and the inner surface of the tire is filled with a spacer comprising a porous material that allows air flow therein. However, it is not disclosed that the sound absorbing material layers having different air permeability are combined to be disposed into the tire cavity and thereby multiple reflections are urged against the sound waves entering and passing through a noise suppressing body to enhance a sound suppressing effect.
On the other hand, JP-A-2005-238888 discloses that the sound absorbing material layer is disposed on an outer peripheral surface of a rim and a sliding layer formed of a resin film is disposed on the outer peripheral surface of the sound absorbing material layer. However, if the resin film having low air permeability is disposed on the outer peripheral side of the sound absorbing material layer, that is, on the tire side, most of the sound waves transmitted from the tread part into the tire cavity are reflected on the surface of the sliding layer, and thereby there are fewer components of the sound waves entering the sound absorbing material layer. Accordingly, the sound absorbing effect cannot be sufficiently demonstrated in the sound absorbing material layer.